This invention relates to apparatus for lifting and handling precast concrete, such apparatus including an anchor insert embedded in a concrete body for engagement with a lifting member having means for attachment to a crane cable or the like for lifting the concrete body. More particularly, the invention pertains to a holder adapted for supporting an anchor insert to be embedded in a concrete slab.
An anchor insert as contemplated by the invention and a representative lifting member employed therewith are disclosed in U.S. Pat. No. 3,499,676. The anchor insert is an elongated member including a shank having an enlarged disc-like foot on one end thereof and, in such embodiment, an enlarged head on the opposite end of the shank for connection to the lifting member. The anchor insert is embedded in a concrete body with its head end projecting therefrom. The foot of the insert serves to anchor it in the concrete, while the head is accessible for connection to the lifting member in lifting the concrete body thereby.
In use of the system illustrated in the above-identified patent, the anchor inserts when employed in a concrete slab or panel being cast horizontally preferably are positioned after placing the concrete. More particularly, each insert is "floated" from a small board resting on the surface of the wet concrete: the head of the insert is enclosed in a rubber plug which is connected to the undersurface of the board, and the remainder of the insert extends downwardly therefrom into the concrete. After the concrete has set, the board and the plug are removed, leaving the insert head exposed in a recess or depression formed in the slab by the plug.
The foregoing method of setting the anchor inserts has certain disadvantages: it is necessary in casting large slabs that the workmen walk over the slabs in order to place the inserts, and this is undesirable. It would be preferable to place the inserts when setting up the form, and before pouring the concrete. Also, the prior float board interferes with screeding therebeneath, and it may leave a recess in the surface of the slab which cannot be finished or decorated in the same manner as the surrounding surface of the slab. Moreover, extra work is required to cast slabs in stacks, one on top of another, inasmuch as the board and the plug must be removed from each insert, and the recess formed by the plug must be filled temporarily, after casting each slab and before casting the next slab in the stack. It would be desirable to provide a means of placing the anchor inserts that would minimize interference with screeding and would also permit casting of one slab on top of another in a stack without need for intervening preparation of the surface of the panel at the location of each insert.